<?php
/**
 * This module contains the XRDS parsing code.
 *
 * PHP versions 4 and 5
 *
 * LICENSE: See the COPYING file included in this distribution.
 *
 * @package OpenID
 * @author JanRain, Inc. <openid@janrain.com>
 * @copyright 2005-2008 Janrain, Inc.
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache
 */

/**
 * Require the XPath implementation.
 */
require_once 'Auth/Yadis/XML.php';

/**
 * This match mode means a given service must match ALL filters passed
 * to the Auth_Yadis_XRDS::services() call.
 */
define('SERVICES_YADIS_MATCH_ALL', 101);

/**
 * This match mode means a given service must match ANY filters (at
 * least one) passed to the Auth_Yadis_XRDS::services() call.
 */
define('SERVICES_YADIS_MATCH_ANY', 102);

/**
 * The priority value used for service elements with no priority
 * specified.
 */
define('SERVICES_YADIS_MAX_PRIORITY', pow(2, 30));

/**
 * XRD XML namespace
 */
define('Auth_Yadis_XMLNS_XRD_2_0', 'xri://$xrd*($v*2.0)');

/**
 * XRDS XML namespace
 */
define('Auth_Yadis_XMLNS_XRDS', 'xri://$xrds');

function Auth_Yadis_getNSMap() {
  return array('xrds' => Auth_Yadis_XMLNS_XRDS, 'xrd' => Auth_Yadis_XMLNS_XRD_2_0);
}

/**
 * @access private
 */
function Auth_Yadis_array_scramble($arr) {
  $result = array();
  
  while (count($arr)) {
    $index = array_rand($arr, 1);
    $result[] = $arr[$index];
    unset($arr[$index]);
  }
  
  return $result;
}

/**
 * This class represents a <Service> element in an XRDS document.
 * Objects of this type are returned by
 * Auth_Yadis_XRDS::services() and
 * Auth_Yadis_Yadis::services().  Each object corresponds directly
 * to a <Service> element in the XRDS and supplies a
 * getElements($name) method which you should use to inspect the
 * element's contents.  See {@link Auth_Yadis_Yadis} for more
 * information on the role this class plays in Yadis discovery.
 *
 * @package OpenID
 */
class Auth_Yadis_Service {

  /**
   * Creates an empty service object.
   */
  function Auth_Yadis_Service() {
    $this->element = null;
    $this->parser = null;
  }

  /**
   * Return the URIs in the "Type" elements, if any, of this Service
   * element.
   *
   * @return array $type_uris An array of Type URI strings.
   */
  function getTypes() {
    $t = array();
    foreach ($this->getElements('xrd:Type') as $elem) {
      $c = $this->parser->content($elem);
      if ($c) {
        $t[] = $c;
      }
    }
    return $t;
  }

  function matchTypes($type_uris) {
    $result = array();
    
    foreach ($this->getTypes() as $typ) {
      if (in_array($typ, $type_uris)) {
        $result[] = $typ;
      }
    }
    
    return $result;
  }

  /**
   * Return the URIs in the "URI" elements, if any, of this Service
   * element.  The URIs are returned sorted in priority order.
   *
   * @return array $uris An array of URI strings.
   */
  function getURIs() {
    $uris = array();
    $last = array();
    
    foreach ($this->getElements('xrd:URI') as $elem) {
      $uri_string = $this->parser->content($elem);
      $attrs = $this->parser->attributes($elem);
      if ($attrs && array_key_exists('priority', $attrs)) {
        $priority = intval($attrs['priority']);
        if (! array_key_exists($priority, $uris)) {
          $uris[$priority] = array();
        }
        
        $uris[$priority][] = $uri_string;
      } else {
        $last[] = $uri_string;
      }
    }
    
    $keys = array_keys($uris);
    sort($keys);
    
    // Rebuild array of URIs.
    $result = array();
    foreach ($keys as $k) {
      $new_uris = Auth_Yadis_array_scramble($uris[$k]);
      $result = array_merge($result, $new_uris);
    }
    
    $result = array_merge($result, Auth_Yadis_array_scramble($last));
    
    return $result;
  }

  /**
   * Returns the "priority" attribute value of this <Service>
   * element, if the attribute is present.  Returns null if not.
   *
   * @return mixed $result Null or integer, depending on whether
   * this Service element has a 'priority' attribute.
   */
  function getPriority() {
    $attributes = $this->parser->attributes($this->element);
    
    if (array_key_exists('priority', $attributes)) {
      return intval($attributes['priority']);
    }
    
    return null;
  }

  /**
   * Used to get XML elements from this object's <Service> element.
   *
   * This is what you should use to get all custom information out
   * of this element. This is used by service filter functions to
   * determine whether a service element contains specific tags,
   * etc.  NOTE: this only considers elements which are direct
   * children of the <Service> element for this object.
   *
   * @param string $name The name of the element to look for
   * @return array $list An array of elements with the specified
   * name which are direct children of the <Service> element.  The
   * nodes returned by this function can be passed to $this->parser
   * methods (see {@link Auth_Yadis_XMLParser}).
   */
  function getElements($name) {
    return $this->parser->evalXPath($name, $this->element);
  }
}

/*
 * Return the expiration date of this XRD element, or None if no
 * expiration was specified.
 *
 * @param $default The value to use as the expiration if no expiration
 * was specified in the XRD.
 */
function Auth_Yadis_getXRDExpiration($xrd_element, $default = null) {
  $expires_element = $xrd_element->$parser->evalXPath('/xrd:Expires');
  if ($expires_element === null) {
    return $default;
  } else {
    $expires_string = $expires_element->text;
    
    // Will raise ValueError if the string is not the expected
    // format
    $t = strptime($expires_string, "%Y-%m-%dT%H:%M:%SZ");
    
    if ($t === false) {
      return false;
    }
    
    // [int $hour [, int $minute [, int $second [,
    //  int $month [, int $day [, int $year ]]]]]]
    return mktime($t['tm_hour'], $t['tm_min'], $t['tm_sec'], $t['tm_mon'], $t['tm_day'], $t['tm_year']);
  }
}

/**
 * This class performs parsing of XRDS documents.
 *
 * You should not instantiate this class directly; rather, call
 * parseXRDS statically:
 *
 * <pre>  $xrds = Auth_Yadis_XRDS::parseXRDS($xml_string);</pre>
 *
 * If the XRDS can be parsed and is valid, an instance of
 * Auth_Yadis_XRDS will be returned.  Otherwise, null will be
 * returned.  This class is used by the Auth_Yadis_Yadis::discover
 * method.
 *
 * @package OpenID
 */
class Auth_Yadis_XRDS {

  /**
   * Instantiate a Auth_Yadis_XRDS object.  Requires an XPath
   * instance which has been used to parse a valid XRDS document.
   */
  function Auth_Yadis_XRDS(&$xmlParser, &$xrdNodes) {
    $this->parser = & $xmlParser;
    $this->xrdNode = $xrdNodes[count($xrdNodes) - 1];
    $this->allXrdNodes = & $xrdNodes;
    $this->serviceList = array();
    $this->_parse();
  }

  /**
   * Parse an XML string (XRDS document) and return either a
   * Auth_Yadis_XRDS object or null, depending on whether the
   * XRDS XML is valid.
   *
   * @param string $xml_string An XRDS XML string.
   * @return mixed $xrds An instance of Auth_Yadis_XRDS or null,
   * depending on the validity of $xml_string
   */
  function &parseXRDS($xml_string, $extra_ns_map = null) {
    $_null = null;
    
    if (! $xml_string) {
      return $_null;
    }
    
    $parser = Auth_Yadis_getXMLParser();
    
    $ns_map = Auth_Yadis_getNSMap();
    
    if ($extra_ns_map && is_array($extra_ns_map)) {
      $ns_map = array_merge($ns_map, $extra_ns_map);
    }
    
    if (! ($parser && $parser->init($xml_string, $ns_map))) {
      return $_null;
    }
    
    // Try to get root element.
    $root = $parser->evalXPath('/xrds:XRDS[1]');
    if (! $root) {
      return $_null;
    }
    
    if (is_array($root)) {
      $root = $root[0];
    }
    
    $attrs = $parser->attributes($root);
    
    if (array_key_exists('xmlns:xrd', $attrs) && $attrs['xmlns:xrd'] != Auth_Yadis_XMLNS_XRDS) {
      return $_null;
    } else if (array_key_exists('xmlns', $attrs) && preg_match('/xri/', $attrs['xmlns']) && $attrs['xmlns'] != Auth_Yadis_XMLNS_XRD_2_0) {
      return $_null;
    }
    
    // Get the last XRD node.
    $xrd_nodes = $parser->evalXPath('/xrds:XRDS[1]/xrd:XRD');
    
    if (! $xrd_nodes) {
      return $_null;
    }
    
    $xrds = new Auth_Yadis_XRDS($parser, $xrd_nodes);
    return $xrds;
  }

  /**
   * @access private
   */
  function _addService($priority, $service) {
    $priority = intval($priority);
    
    if (! array_key_exists($priority, $this->serviceList)) {
      $this->serviceList[$priority] = array();
    }
    
    $this->serviceList[$priority][] = $service;
  }

  /**
   * Creates the service list using nodes from the XRDS XML
   * document.
   *
   * @access private
   */
  function _parse() {
    $this->serviceList = array();
    
    $services = $this->parser->evalXPath('xrd:Service', $this->xrdNode);
    
    foreach ($services as $node) {
      $s = & new Auth_Yadis_Service();
      $s->element = $node;
      $s->parser = & $this->parser;
      
      $priority = $s->getPriority();
      
      if ($priority === null) {
        $priority = SERVICES_YADIS_MAX_PRIORITY;
      }
      
      $this->_addService($priority, $s);
    }
  }

  /**
   * Returns a list of service objects which correspond to <Service>
   * elements in the XRDS XML document for this object.
   *
   * Optionally, an array of filter callbacks may be given to limit
   * the list of returned service objects.  Furthermore, the default
   * mode is to return all service objects which match ANY of the
   * specified filters, but $filter_mode may be
   * SERVICES_YADIS_MATCH_ALL if you want to be sure that the
   * returned services match all the given filters.  See {@link
   * Auth_Yadis_Yadis} for detailed usage information on filter
   * functions.
   *
   * @param mixed $filters An array of callbacks to filter the
   * returned services, or null if all services are to be returned.
   * @param integer $filter_mode SERVICES_YADIS_MATCH_ALL or
   * SERVICES_YADIS_MATCH_ANY, depending on whether the returned
   * services should match ALL or ANY of the specified filters,
   * respectively.
   * @return mixed $services An array of {@link
   * Auth_Yadis_Service} objects if $filter_mode is a valid
   * mode; null if $filter_mode is an invalid mode (i.e., not
   * SERVICES_YADIS_MATCH_ANY or SERVICES_YADIS_MATCH_ALL).
   */
  function services($filters = null, $filter_mode = SERVICES_YADIS_MATCH_ANY) {
    
    $pri_keys = array_keys($this->serviceList);
    sort($pri_keys, SORT_NUMERIC);
    
    // If no filters are specified, return the entire service
    // list, ordered by priority.
    if (! $filters || (! is_array($filters))) {
      
      $result = array();
      foreach ($pri_keys as $pri) {
        $result = array_merge($result, $this->serviceList[$pri]);
      }
      
      return $result;
    }
    
    // If a bad filter mode is specified, return null.
    if (! in_array($filter_mode, array(SERVICES_YADIS_MATCH_ANY, 
        SERVICES_YADIS_MATCH_ALL))) {
      return null;
    }
    
    // Otherwise, use the callbacks in the filter list to
    // determine which services are returned.
    $filtered = array();
    
    foreach ($pri_keys as $priority_value) {
      $service_obj_list = $this->serviceList[$priority_value];
      
      foreach ($service_obj_list as $service) {
        
        $matches = 0;
        
        foreach ($filters as $filter) {
          if (call_user_func_array($filter, array($service))) {
            $matches ++;
            
            if ($filter_mode == SERVICES_YADIS_MATCH_ANY) {
              $pri = $service->getPriority();
              if ($pri === null) {
                $pri = SERVICES_YADIS_MAX_PRIORITY;
              }
              
              if (! array_key_exists($pri, $filtered)) {
                $filtered[$pri] = array();
              }
              
              $filtered[$pri][] = $service;
              break;
            }
          }
        }
        
        if (($filter_mode == SERVICES_YADIS_MATCH_ALL) && ($matches == count($filters))) {
          
          $pri = $service->getPriority();
          if ($pri === null) {
            $pri = SERVICES_YADIS_MAX_PRIORITY;
          }
          
          if (! array_key_exists($pri, $filtered)) {
            $filtered[$pri] = array();
          }
          $filtered[$pri][] = $service;
        }
      }
    }
    
    $pri_keys = array_keys($filtered);
    sort($pri_keys, SORT_NUMERIC);
    
    $result = array();
    foreach ($pri_keys as $pri) {
      $result = array_merge($result, $filtered[$pri]);
    }
    
    return $result;
  }
}
